There's no scientific evidence that city life makes people more depressed than rural life, but schizophrenia rates do differ significantly between the 2 settings, a recent International Conference on Urban Health was told.
In the past 10 years, major birth cohort studies in developed countries have revealed that the incidence of schizophrenia is about 2 times higher among people in cities, reported Dr. Ezra Susser, head of epidemiology at Columbia University's Mailman School of Public Health.
“It's not clear if it is birth in cities, or upbringing in cities, but there is something about city living that increases risk,” he said. Where you are born and brought up is a larger contributing factor to risk than genetic predisposition. Indeed, 34.6% of cases would be prevented if people were not born and brought up in cities, compared to 5.4% of cases that would be prevented if people did not have parents or siblings who suffered from the illness, Susser told participants at the New York conference.
The higher rate in urban areas may be due to environmental toxins, the social context that people live in, and contagion, including prenatal infections.
The studies also reveal a “dose response”: the more urban the setting, the higher the risk. “This is one of the most solid findings in schizophrenia today,” said Susser. But the association with urban living has not received enough attention because current research centres on neural imaging and pharmacology, Susser says. — Ann Silversides, Toronto